1. Field of the Invention
This invention relates to a method of, and an apparatus for building green tires by forming a band consisting of belt plies and a tread and then combining the formed band with a green case to form a green tire. More particularly it relates to a transfer apparatus for transferring cylindrical members such as belts, tread bands and the like in tire producing processes from one forming drum to another forming drum.
2. Description of Related Art
Tire building apparatus for building green tires have been known. For example, there is known one type of apparatus which includes one band forming drum, a plurality of belt ply supply means arranged one above the other on one side of the band forming drum for supplying belt plies of different kinds, and one tread supply means arranged above the belt ply supply means for supplying treads to the band forming drum. The apparatus further includes one taking-out device for removing from the band forming drum a band formed by successively winding the belt plies and a tread supplied to the band forming drum and for transferring the removed band, and a tire forming drum on which a green case is combined with the band transferred by the taking-out means to form a green tire.
In forming a green tire by the use of such an apparatus, first the belt plies of the different kinds are successively supplied from the belt ply supply means onto the band forming drum, while it is being rotated so that the belt plies are wound around the band forming drum. Thereafter, the tread is supplied from the tread supply mean and wound over the belt plies on the band forming drum to form a band. The formed band is then removed from the band forming drum by means of the taking-out device and transferred to the tire forming drum. In this case, since a green case has been previously fitted on the tire forming drum, the green case and the band are combined on the tire forming drum to form a green tire.
With such method and apparatus for building tires, as one set of belt ply supply means and one tread supply means are arranged for one band forming drum, there is a problem in that the apparatus is complicated in construction and large-sized.
Transfer apparatus for transferring cylindrical members between expansible and contractible forming drums have been known. For example, known transfer apparatus includes rails arranged between both the forming drums, and a transfer member having a ring member on its upper portion and slidably movable on the rails toward and away from the forming drums. The ring member has a chuck capable of expanding and contracting to grasp the cylindrical member on its outside. In transferring the cylindrical member with such a transfer apparatus, first the transfer member is moved toward one forming drum so that the ring member is loosely fitted on the forming drum. Thereafter, the chuck is contracted to reduce its diameter so that the cylindrical member on the forming drum is grasped on its outside by the chuck, while the one forming drum is contracted to reduce its diameter and the transfer member is then moved toward the other forming drum so that the ring member is loosely fitted on the forming drum. The other forming drum is then expanded to increase its diameter to support the cylindrical member on its inside, while the chuck is expanded to increase its diameter to release the cylindrical member, thereby transferring the cylindrical member from the transfer member to the other forming drum.
Such a transfer apparatus makes it possible to readily transfer cylindrical members in the case wherein the forming drums are coaxial with each other or there is no obstruction between the forming drums. However, in the event that, for example, the forming drums are not coaxial with each other or axes of the forming drum are in parallel with but spaced from each other or any stationary member is provided between the coaxial forming drums, the mid portions of the rails are necessarily curved in a complicated manner in order to accomplish the transfer of the relevant member between the forming drums. As a result, however, the heavy transfer member must be moved along the complicated passage so that the entire installation becomes bulky and the transfer of the member takes much time thereby lowering the operation efficiency.